The present invention relates to a sealing arrangement between two radially adjoining components of an assembly rotating during operation, in particular the rotor and rotating vane of a gas turbine component, with a seal element in a depression of an inner one of the two components at the boundary surface towards the outer one of the two components, as well as a method for the production of a sealing joint between two components.
Steam-cooled gas turbine components require very reliable seals for the transport of the steam used for cooling, since a leak on the one hand reduces the efficiency of the thermodynamic process and on the other hand reduces the life span of the component due to the resulting poorer cooling. There are special requirements for the sealing joints of rotating components, for example, for turbine rotating blades, since the steam in these cases must be passed from the resting system into the rotating system. In the same way, the steam must again be returned from the rotating component into the resting system, so that typically two sealing joints per component are necessary. As a rule, such sealing joints are required between the cooling channels in the rotor plate and between the cooling channels in the rotating blades of the turbine. The rotating blades are hereby suspended with their blade base in corresponding grooves or guides in the rotor plate, whereby both the groove and the blade base are provided with appropriate complementary, usually pine-tree-shaped geometries. The transition of the cooling channels from the rotor plate to the rotating blade and vice versa takes place within this groove of the rotor plate.
Because of the required seals, the assembly of the rotating blades and the rotor, during which the blade base is pushed laterally into the corresponding groove on the rotor plate, is very complex.
An example of a sealing joint between the rotor plate and rotating blades of a turbine component is shown in U.S. Pat. No. 5,318,404. The sealing arrangement shown there is formed by depressions in the blade base and rotor plate that respectively face each other, and in which a sleeve-like sealing element is located. This sealing element seals the joint between the cooling channels in the rotating blade and the cooling channels in the rotor plate. To permit a better installation of the sleeve-like sealing elements, which in the installed state extend over the full radial extension of the chamber formed by the depressions, it is suggested that these sealing elements are designed with radial elasticity. During assembly, they are then pushed completely into the depression on the rotor disk when the rotating blade is pushed in, and, because of their preload, expand into the corresponding depression at the base of the rotating blade as soon as the two depressions are located on top of each other. The sealing elements are hereby designed so that, even after the assembly of the rotating blades, their preload will still be sufficient to achieve the pressure against the rotor plate and rotating blade required for the sealing effect.
Such a design of the sealing joint indeed facilitates the assembly of the rotating blades when compared to rigid sealing elements; however, because the sealing elements must be pushed against the preload during the installation of the rotating blades, complications may still be encountered.
Based on this start of the art, the invention is based on the objective of disclosing a sealing arrangement as well as a method for producing a sealing joint between two components that enable an easier installation of the components, in particular of the rotating blades to the rotor plate of a gas turbine component.
The sealing arrangement according to the invention between two radially adjoining components of an assembly rotating during operation, in particular the rotor and rotating vane or blade base of a gas turbine component, is provided in the known manner with a sealing element in a depression of an inner one of the two components at the boundary surface towards the outer one of the two components. In the present sealing arrangement, the sealing element is designed in such a way that, during the assembly, i.e., while it being inserted or placed into the depression, it does not project or does project only slightly beyond the depression, and during the rotation of the assembly, as a result of the centrifugal force acting on it, produces a sealing joint between the components. The radial dimension of the sealing elementxe2x80x94in relation to the rotation axis of the assemblyxe2x80x94therefore must be chosen so that (during the insertion of the sealing element) it does not exceed or does only insignificantly exceed the depth of the depression at the inner component, i.e., the component that is located closer to the rotation axis. This facilitates an easy pushing in of a rotating blade into the dove-tail- or pine-tree-shaped groove on the rotor plate, since the sealing element set into the depression no longer interferes with the sliding process. An arrangement projecting slightly beyond the depression here means that the sealing element only projects beyond the depression to such an extent that it just does not interfere during the assembly. In contrast to the state of the art described previously, this technique does not require a pressing down of the sealing element.
The actual sealing effect in the present sealing arrangement is achieved only with a rotation of the assembly, during which the sealing element is pressed with its sealing surfaces against the sealing surfaces of the outer component and, if required, against the inside wall of the depression. Different designs are possible for the sealing elements required for this and are described in the secondary claims as well as in the exemplary embodiments.
One principal design option is that the entire sealing element is moved, under the influence of centrifugal force, towards the second component and is pressed against it, whereby laterally deformable and/or elastic edge areas at the same time are pressed against the side wall of the depression of the inner component. According to another possibility, a lower part of the sealing element is fixed in the depression, and an upper or outer part is designed in an expandable manner. The expandable part is hereby pressed under application of a centrifugal force against the outer component. In all cases, the outer component can be constructed either without or with a corresponding depression.
Suitable materials for sealing elements are known to the expert. In the present sealing arrangement, these may be elastic or partially elastic sealing elements that return to their starting shape in the resting state of the assembly. It is, however, also possible to use deformable materials as sealing elements that change their shape as a result of the centrifugal force acting on them in order to bring about the necessary sealing effect, and to maintain this last shape once the assembly is turned off or is in its resting state. In the first case, the sealing elements return to their starting position in the depression in a corresponding position of the assembly in the resting state, so that the rotating blades also can be easily disassembled. In the second case, the sealing elements must be destroyed during the disassembly of the rotating blades.
The sealing elements or seals of the present sealing arrangement that are only pressed into the seal seat by centrifugal force during the rotation of the assembly can be very simply constructed. Nevertheless, when used in gas turbines, they seal very effectively since high centrifugal forces (approximately 10,000 g) are achieved at the respective speeds. The seals can be designed so that they return to their starting position when the machine stands still, which facilitates the removal of the blades. This can be supported by additional machine elements, such as springs.
Another embodiment of a sealing arrangement according to the invention used to realize the above mentioned objective also uses centrifugal force in order to create the sealing joint. This alternative embodiment also uses a sealing element that does not or does only slightly project beyond the depression on the inner component. The outer component is hereby suspended or attached in such a way that the forces occurring during the rotation of the assembly apply a tilting moment to the outer component, which causes it to be pressed against the seal. In this manner, the sealing joint also is only created during operation of the assembly in this case. The sealing element hereby can be constructed in an even simpler manner and should project slightly beyond the depression, but only to such an extent that it does not hinder the installation of the rotating blade.
In principle, the present arrangement can be used for any sealing tasks. However, it is preferably used for creating a sealing joint between cooling channels in the two radially adjoining components.
The method according to the invention for the production of a sealing joint between two components also uses the action of a centrifugal force in order to create the sealing joint. Hereby a sealing element is set into the depression of the first component. The sealing element is designed in such a way that it does not or does only slightly project beyond the depression after it has been inserted into the this depression and is able to create the sealing joint after being acted on by a force directed towards the second component. After the sealing element has been placed into the depression and the second component has been assembled, a centrifugal force directed towards the second component acts on the sealing element, which centrifugal force is produced in that both components of the assembly are brought to rotate or they are spun in a suitable manner.
This method makes it possible to produce a sealing joint even between components that do not rotate during operation by spinning them accordingly prior to their use. Naturally, the latter case requires that a sealing element is used that no longer returns into its starting shape and/or its starting position after the spinning. A sealing element that is solid during assembly and melts during the spinning when exposed to an increased temperature can be used especially advantageously for this. The molten mass then adapts to the gap to be sealed, so that an optimum seal is achieved after cooling.
Naturally, the present sealing arrangement and the described sealing method can be used for any sealing tasks. The application of the invention is not limited to the preferred use in gas turbine components, even though it offers significant advantages there.